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Differential patterns of dynamic cardiovascular regulation as a function of task
B E Hurwitz1, R A Nelesen, P G Saab
1Department of Psychology, Univeristy of Miami, Coral Gables, FL 33124.
Insights
Different behavioral stressors uniquely impact cardiovascular responses. Impedance cardiography reveals distinct hemodynamic patterns during speech, mirror tracing, and cold pressor tests, aiding interpretation of blood pressure changes.
Area of Science:
- Cardiovascular Physiology
- Behavioral Medicine
Background:
- Interpreting cardiovascular reactivity can be challenging when blood pressure and heart rate increase simultaneously.
- Understanding the underlying hemodynamic mechanisms is crucial for accurate interpretation.
Purpose of the Study:
- To investigate distinct hemodynamic responses to various behavioral stressors.
- To differentiate the contributions of cardiac output and total peripheral resistance to blood pressure changes.
Main Methods:
- Utilized impedance cardiography, electrocardiogram, and phonocardiogram recordings.
- Measured cardiovascular responses during speech stress, mirror tracing, and cold pressor tests.
- Analyzed cardiac output, total peripheral resistance, and systolic time intervals.
Main Results:
- All stressors increased blood pressure and heart rate, with speech eliciting the largest changes.
- Speech preparation increased cardiac output; speech involved both cardiac output and total peripheral resistance.
- Mirror tracing and cold pressor tests primarily increased total peripheral resistance.
- Observed sex differences in myocardial contractility at rest, despite similar hemodynamic responses to stressors.
Conclusions:
- Different behavioral stressors evoke distinct hemodynamic patterns.
- Impedance cardiography provides valuable insights into dynamic cardiovascular processes during stress.
- Findings enhance the understanding of cardiovascular reactivity to diverse challenges.
Abstract:
In cardiovascular reactivity studies, interpretations of the processes supporting the blood pressure response may become problematic when systolic blood pressure, diastolic blood pressure, and heart rate all increase in response to a behavioral challenge. Therefore, in addition to evaluating these cardiovascular responses, this study examined cardiac output, total peripheral resistance and systolic time intervals derived from impedance cardiogram, electrocardiogram and phonocardiogram recordings during a speech stressor, a mirror tracing task, and a foot cold pressor test. All of the behavioral stressors elicited increases in blood pressure and heart rate, with the largest changes occurring during the overt speech. Based on the examination of the response patterns of the underlying hemodynamic variables it would appear that, in both men and women, the blood pressure increase during the speech preparation period was supported by increased cardiac output; the speech itself resulted in a mixed pattern of increased cardiac output and total peripheral resistance; whereas, the mirror tracing and cold pressor tasks produced increased total peripheral resistance. Although men and women produced similar response patterns to the behavioral challenges, sex differences in the estimates of myocardial contractility were observed during rest. These results provide evidence that different behavioral stressors can produce a distinct yet integrated pattern of responses, whose differences may be revealed, when impedance cardiography is used, to derive sufficient response measures for assessing dynamic cardiovascular processes.